Part 1 of 3
LAMPS/LIGHTING - EXTERIORTurn Signal & Hazard Warning System
A turn signal and hazard warning system is standard factory-installed safety equipment on this model. The turn signal and hazard warning system includes the following major components, which are described in further detail elsewhere in this service information:
- Combination Flasher - The electronic combination flasher is installed in the relay and fuse block, which is located behind the fuse access panel on the left outboard end of the instrument panel.
- Hazard Warning Switch - The hazard warning switch is integral to the multi-function switch on the left side of the steering column. The hazard warning switch button protrudes from a dedicated opening in the shroud on the top of the steering column, just below the steering wheel.
- Turn Signal Cancel Cam - The turn signal cancel cam is integral to the clockspring, which is located beneath the steering column shrouds at the top of the steering column, just below the steering wheel.
- Turn Signal Indicators - The two turn signal indicators, one right and one left, are integral to the ElectroMechanical Instrument Cluster (EMIC) located in the instrument panel.
- Turn Signal Lamps - The front turn signal lamps are integral to the lower front outboard ends of the headlamp modules, located just outboard of the two sides of the radiator grille opening. The rear turn signal lamps are integral to the taillamp modules located on each side of the rear cargo door opening at the rear of the vehicle.
- Turn Signal Switch - The turn signal switch is integral to the multi-function switch on the left side of the steering column. The multi-function switch control stalk that actuates the turn signal switch protrudes from a dedicated opening in the steering column shrouds on the left side of the column, just below the steering wheel.
Hard wired circuitry connects the turn signal and hazard warning system components to each other through the electrical system of the vehicle. These hard wired circuits are integral to several wire harnesses, which are routed throughout the vehicle and retained by many different methods. These circuits may be connected to each other, to the vehicle electrical system and to the turn signal and hazard warning system components through the use of a combination of soldered splices, splice block connectors and many different types of wire harness terminal connectors and insulators.
The turn signal system operates on battery current received on a fused ignition switch output (run-acc) circuit so that the turn signals will only operate with the ignition switch in the ON or Accessory positions. The hazard warning system operates on non-switched battery current received on a fused B(+) circuit so that the hazard warning remains operational regardless of the ignition switch position. When the turn signal (multi-function) switch control stalk is moved up (right turn) or down (left turn), the turn signal system is activated. When the turn signal system is activated, the circuitry of the turn signal switch and the combination flasher will cause the selected (right or left) turn signal indicator, front park/turn signal lamp, and rear tail/stop/turn signal lamp to flash ON and OFF. With the hazard warning (multi-function) switch in the ON position, the hazard warning system is activated. When the hazard warning system is activated, the circuitry of the hazard warning switch and the combination flasher will cause both the right side and the left side turn signal indicators, front park/turn signal lamps, and rear tail/stop/turn signal lamps to flash ON and OFF.
The hard wired circuits of the turn signal and hazard warning system can be diagnosed using conventional diagnostic tools and methods. Refer to the owner's manual in the vehicle glove box for more information on the features, use and operation of the turn signal and hazard warning system.
BRAKE LAMP SWITCH
The plunger type brake lamp switch is mounted on a bracket attached to the brake pedal support.
CAUTION: The switch can only be adjusted during initial installation. If the switch is not adjusted properly a new switch must be installed.
The primary function of the switch is to turn ON the brake lamps during braking. The switch is also used to send signals to components that must know when the brakes are applied, such as the Powertrain Control Module (PCM), which uses the signal to cancel speed control. The CAB uses the brake switch signal to monitor brake pedal application. When the switch contacts open (brakes applied), the CAB receives the brake applied signal. The CAB then monitors the RWAL system to anticipate the need for an RWAL stop.
COMBINATION FLASHER
The combination flasher is located in the relay and fuse block, which is concealed behind the fuse access panel on the left outboard end of the instrument panel. The combination flasher is a smart relay that functions as both the turn signal system and the hazard warning system flasher. The combination flasher has fourteen blade-type terminals that connect it to the vehicle electrical system through fourteen matching cavities in the fuse and relay block; however, only eleven of the combination flasher terminals are used in this application. The combination flasher contains active electronic Integrated Circuitry (IC) elements. This flasher is designed to handle the current flow requirements of the factory-installed lighting. If supplemental lighting is added to the turn signal lamp circuits, such as when towing a trailer with lights, the combination flasher will automatically try to compensate to keep the flash rate the same.
The combination flasher cannot be repaired or adjusted and, if faulty or damaged, it must be replaced.
The combination flasher has fourteen blade-type terminals, but only eleven are used in this application. These eleven terminals are intended for the following inputs and outputs: fused B(+), fused ignition switch output, right turn switch sense, left turn switch sense, hazard flasher signal, brake lamp switch output, two outputs each for the right and left turn signal circuits, and ground. Constant battery voltage is supplied to the flasher so that it can perform the hazard warning function, and ignition switched battery voltage is supplied for the turn signal function. The Integrated Circuit (IC) within the combination flasher contains the logic that controls the flasher operation and the flash rate. The IC receives separate sense ground inputs from the multi-function switch for the hazard flasher, right turn signal, and left turn signal. A special design feature of the combination flasher allows it to "sense" that a turn signal circuit or bulb is not operating, and provide the driver an indication of the condition by flashing the remaining bulbs in the affected circuit at a higher rate (120 flashes-per-minute or higher). Conventional flashers either continue flashing at their typical rate (heavy-duty type), or discontinue flashing the affected circuit entirely (standard-duty type).
Because of the active electronic elements within the combination flasher, it cannot be tested with conventional automotive electrical test equipment. If the combination flasher is believed to be faulty, test the turn signal and hazard warning system. Then replace the combination flasher with a known good unit to confirm system operation. (Refer to LAMPS/LIGHTING - EXTERIOR/TURN SIGNAL & HAZARD WARNING SYSTEM - DIAGNOSIS AND TESTING).